Puncture instrument

ABSTRACT

A device for puncturing cortical bone. The device consists of a cannula and inside of it an axially movable needle. The distal end of the needle has an eccentrically shaped tip which, by drilling, forms a hole, larger than the outer diameter of the needle, through corticalis, whereupon the enclosing cannula can be inserted into the drilled hole. In this way the cannula&#39;s position in the bone is secured and the cannula functions as a fixed anchored guiding channel for further sampling or treatment.

This application is a divisional, of application Ser. No. 08/037,114,filed Mar. 23, 1993 now U.S. Pat. No. 5,423,824.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention primarily relates to a device for puncturing hardtissue in, for example, humans or animals, and to a technique forpuncturing in this type of tissue.

The skeleton is the site of many different pathological lesions, blooddiseases etc. The lesions are often visible on X-rays of the skeleton,but in general, it is not possible, using X-ray, to determine the causeof the lesion. In order to with certainty determine the nature of thelesion, parts of the bone must be removed and examined under microscope.

Biopsy sampling of the bone is difficult to perform due to the fact thatthe lesion is often surrounded by the hard outer surface of the boneknown as corticalis.

2. Discussion of the Related Art

One way to gain access to the lesion through the cortical bone is tointroduce a conventional spiral drill equipped with a cannula, drillthrough the cortical bone, then remove the drill. The cannula remains inplace in the soft tissue, but cannot be inserted through the drilledhole in the cortical bone because the outer diameter of the cannula islarger than the diameter of the drilled hole. The disadvantage is thatthe cannula can easily be moved out of position, making it difficult torelocate the drilled hole in order to, for example, introduce a biopsyneedle. This disadvantage is especially apparent when performing apuncture not at a right angle to the bone surface.

Currently, two main methods are used to obtain biopsy samples of bone:operative biopsy and percutaneous needle biopsy. An operative procedureoften yields good results but requires general anesthesia as well assubstantial resources and cost. Percutaneous needle biopsy is performedunder a local anaesthetic. The needle usually consists of a sharpened orsaw-toothed sampling cannula which is introduced into the lesionresulting in the excision of a biopsy sample. Upon introduction, astylet is inserted into the cannula forming a sharp distal tip in orderto facilitate entry into the soft tissue. Examples of this type ofneedle are described in European Pat. No. 0,296,421 (the Ostycut needle)and in U.S. Pat. No. 3,628,524 (the Jamshidi needle).

Existing needle biopsy methods have the substantial disadvantage of notbeing able to easily penetrate cortical bone. Common biopsy needles suchas, for example, Jamshidi and ostycut all have a needle tip which canonly penetrate thin or soft cortical bone. This is due to the fact thatthe tip does not clear away the material like a drill, but insteadwedges itself in using considerable insertion force combined withrotation. A further disadvantage is that the substantial friction whichresults between the needle and the cortical bone hinders themanipulation of the needle towards the target and causes development ofheat which can be painful to the patient. Also common are needle typesin which the distal end of the cannula is saw-toothed. Examples of thistype of needle are described in U.S. Pat. No. 4,306,570 (the Corbneedle). The disadvantage of the saw-teeth, however, is that the teethbecome plugged with drill chips when the depth of the cut exceeds thelength of the teeth.

Furthermore, the saw-teeth must be covered by an outer protectivecannula upon insertion into the soft tissue of the body in order toavoid damage. This increases the requisite outer diameter of the needle.

Drills and drill units for making holes having a greater diameter thanthe diameter of the drill itself are as such, already in existence (see,for example, U.S. Pat. Nos. 4,635,738, 4,878,794, 5,009,271). Thesepatents concern primarily drilling in the earth, for example, for oil,and lie therefore outside the technical area dealt with by the presentinvention.

SUMMARY OF THE INVENTION

Therefore, there is a need for a device or method to puncture hardtissue in which the drill can be removed while the cannula remains inplace.

There is also a need for a device or method to puncture hard tissue foruse in performing a puncture not at a right angle to the bone.

There is further a need for a needle biopsy device and method which canalso penetrate hard tissue such as cortical bone.

Another need is for a device and method to puncture hard tissue whichclears away the material.

Yet another need is for a device and method to puncture hard tissuewhich is less painful to the patient.

The present invention (henceforth called "the puncture instrument"),which is defined in the attached claims, eliminates the disadvantagesthat occur with the known biopsy methods described above.

According to one aspect of the invention, there is provided a device forpuncturing hard tissue in humans or animals. The apparatus includes acannula, with a distal end and a proximal end, forming a void. A needlewith a distal end and a proximal end is removably and rotatably insertedwith the void. The distal end of the needle may extend from the distalend of the cannula. A tip is disposed on the distal end of the needle,with a radial displacement in relation to an axial center of the needle.

In one preferred embodiment, the needle is shaped like a spiral drillhaving one or more drill cutters.

In another preferred embodiment, the needle is equipped with a tip whichis radially displaced from the geometrical central axle of the needle,and the tip includes a point angle formed by the drill cutters.

In another aspect, the invention is manifested as a method for accessinghard tissue in humans or animals.

According to the method, the soft tissue around the hard tissue ispunctured by a needle inserted within a cannula. The needle drills ahole with a diameter larger than the diameter of the cannula in the hardtissue. The cannula is inserted into the hole. The needle is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail below, with referenceto the attached drawings, in which:

FIG. 1 is a schematic longitudinal view of the puncture instrument inaccordance with the invention;

FIG. 2 is a longitudinal section through the cannula of the instrument;

FIG. 3 is a longitudinal view of an embodiment of the instrument'sneedle;

FIG. 4 is a longitudinal view of the embodiment's drill tip rendered inFIG. 3;

FIG. 5 is an end view of the drill tip;

FIG. 6 is a schematic drawing which describes the wobbling function ofthe drill during use;

FIG. 7 is a longitudinal view of an alternative embodiment of a drilltip;

FIG. 8 is a longitudinal view of the instrument equipped with a needlehaving a smooth tip as well as an alternative embodiment of the handle;

FIG. 9 is a longitudinal view which shows a depth-stop;

FIG. 10 shows an alternative embodiment of the drill's tip; and

FIG. 11 is the longitudinal view shown in FIG. 4 with explanatorymarkings;

FIG. 12 is the end view shown in FIG. 5 with explanatory markings; and

FIG. 13 is a longitudinal view shown in FIG. 8 illustrating a needle andcannula with coatings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The puncture instrument 1 in accordance with the invention, shown inFIG. 1 consists of a cannula 2, the distal end 3 of which is externallytapered 3'. Around the cannula's proximal end 4 a handle 4' is attached.Fitted into the cannula is an axially movable solid needle 5 or stylet.Around the needle's 5 proximal end 6, a handle 6' is attached.

FIG. 2 shows a longitudinal section through the cannula. Preferably, thecannula has an outer diameter of 2 mm, an inner diameter of 1.6 mm and atotal length of approximately 120 mm, but the dimensions may vary withinbroad limits for special applications. The distal end 3 of the cannula 2is externally tapered to a sharp edge 3'. The handle 4' on the cannulais equipped with an internal taper 15 so that a syringe with aluer-attachment can be connected, for example, for aspiration orinjection.

FIG. 3 shows a longitudinal view of a first embodiment of the solidneedle. Approximately 10 mm of the needle's distal end 7 is shaped likea spiral drill 7'. Preferably, the needle has an outer diameter of 1.6mm. The length of the needle is proportioned so that the drill tipextends approximately 5 mm out from the distal end 7 of the cannula inassembled condition, so that the drill's discharge of chips is notinhibited by the cannula. The needle's dimensions can, obviously, alsovary according to application.

FIG. 4 shows a longitudinal view of the needle's tip in anotherembodiment, in which the tip is shaped like a conventional spiral drillwith two drill cutters 9, 9', but the difference is that the tip 8formed by the drill cutters does not, as is the normal case, coincidewith the geometrical center axis of the needle. Preferably, the needlehas an outer diameter of 1.6 mm and the drill tip is displacedapproximately 0.3 mm relative to the needle's center axis. In thisexample, however, the long cutter 9 has a radius of 1.1 mm and the shortcutter 9' a radius of 0.5 mm. The drill tip's point angle 12 ispreferably 80 degrees. The greater angle reduces the ability of thedrill to enter bone during oblique punctures and a smaller angleincreases the drill's requisite insertion force.

FIG. 5 shows an end view of the needle's drill tip. The needle'sgeometrical center of rotation is marked 10 and the position of thedrill tip is marked 8.

FIG. 6 shows schematically how the needle's drill tip works. Whendrilling into bone 11 the drill tip 8 functions as a guide and forcesthe drill to "wobble" around in the hole with the drill tip as thecenter of rotation. In this way, the drilled hole is given a radiuswhich is equivalent to the radius of the longest drill cutter 9.Consequently, the diameter of the hole will be 2.2 mm if the radius ofthe longest drill cutter is 1.1 mm.

FIG. 7 shows an alternative embodiment of the needle's drill tip. Inthis embodiment, the outer part 13 of the long cutter 9 has a greaterpoint angle 14, preferably 180 degrees. This gives the advantage thatthe drill's requisite insertion force is reduced, while at the same timethe drill tip's point angle 12, which is 80 degrees, still facilitatesentry into the bone during oblique punctures. The handles 4', 6' on thecannula 2 and the respective needle 5 are preferably made of plastic andequipped with external grooves (not shown) which provide a good grip formanual rotation and also function as driving slots when the instrumentis assembled into a drill chuck.

If a drill is used, it is preferably electrically or pneumaticallypowered. Electrical battery power is preferable due to the easymanageability since no connecting cord is necessary. Suitable axlerotation speed is 100-300 rpm. The drill can also be manually operated,e.g., using a gear wheel equipped with a crank. The manual drive issimple in design but a disadvantage is that the needle is easily jarredout of place during cranking.

Dental-type drill machines are also possible alternatives.

The needle tip is preferably made by grinding a solid piece of wire. Thespiral shaped grooves in the tip are cut by moving the wire axiallyunder a grinding disc while at the same time rotating the needle withthe desired tip 8 as the axle of rotation. The relationship between theaxial feeding of the needle and the rotation is adjusted so that theintended spiral angle is obtained. The axial surfaces on the tip are cutwith clearance behind the cutting edges as in a conventional spiraldrill.

An alternative embodiment of the needle FIG. 10 is that the drill tip 28is formed like a taper with external spiral threads, and the drillcutters 9 join the base of the taper. When drilling, the taper's threadshelp to feed the drill forward and reduce the insertion force required.

The drill tip can also be truncated and equipped with a small transverseedge. This reduces the drill's requisite insertion force, but thedisadvantage is that it is more difficult for the tip to enter the boneduring oblique punctures.

Another alternative embodiment is that the drill tip 8 is displacedcorresponding to the radius of the whole needle, that is, the tipcoincides with the needle's circumference or outer diameter. The drilltip then consists of a single long drill cutter, and the drill thereforewill fill a hole equivalent to double the size of the needle's diameter.

The handle 4' on the cannula 2 is equipped with an internal taper 15 sothat a syringe with a luer connector can be attached for aspiration orinjection.

FIG. 8 shows an alternative embodiment where the handle is made with athreaded 16 or bayonet connection (not shown) so that the cannula 2 andthe needle 5 can be locked relative to one another in order to simplifythe handling during insertion and drilling. In this example the needlehas a smooth tip 17 meant to be able to replace the drill-shaped needleduring puncture of skin and soft tissue.

FIG. 9 shows a depth-stop 19. During sampling through the cannula, it isof value to be able to limit how deep the sampling needle 20 shall beinserted relative to the cannula 22, so that the puncture will be madeonly up to the depth desired. The depth-stop consists of a pin with anumber of kerfs (or fractural impressions) 21 equally distributed,preferably made of plastic so that the pin 21 can easily be broken offat any kerf to the desired length and in this way functions as adepth-stop for, for example, a biopsy needle.

FIG. 11 illustrates the longitudinal view of the needle shown in FIG. 4,and FIG. 12 illustrates the end view of the needle shown in FIG. 5.FIGS. 11 and 12 include explanatory markings to assist in identifyingportions of the needle. The needle includes the body of the needle 101and what is referred to in the claims as the "drill tip" 105. The bodyof the needle 101 includes drill threads 103a, 103b. The drill threads103a, 103b have outer edges 109a, 109b. The outer edges 109a, 109b forman outer diameter 111 of the needle.

The drill tip 105 includes the long cutter 9 and the short cutter 9'.The drill tip 105 is defined as beginning where the outer edges 109a,109b of the drill threads 103a, 103b terminate. The drill tip 105 has amaximum diameter 114 which corresponds to the outer diameter 111 of theneedle.

The long cutter 9 has a proximal end 113a and a distal end 115a, and theshort cutter 9' has a proximal end 113b and a distal end 115b. Theproximal end 113b of the short cutter 9' intersects the outer diameter111 of the needle at the termination of the outer edge 109b of the drillthread 103b. An axis of the proximal end 113a of the long cutter 9intersects the outer diameter 111 of the needle at the termination ofthe outer edge 109a of the other drill thread 103a. In the illustratedembodiment, the proximal end 113a of the long cutter 9 intersects theouter diameter 111 of the needle at the termination of the outer edge109a of the drill thread 103a.

A drill point 107 is provided at an intersection of the axes of thecutters 9, 9', where the distal ends 113a, 113b of the cutters 9, 9'meet.

As illustrated in FIG. 13, the cannula 2 and the needle 17 also may becoated with a coating 121, 123 of friction-reducing material, or of ahydrophilic material.

In order to puncture cortical bone for sampling or treatment of alesion, the puncture instrument is used preferably in the following way:

The instrument is inserted, assembled in accordance with FIG. 1, intothe soft tissue towards the cortical bone surface. If the insertion ismade through sensitive areas, for example, near nerve pathways, theneedle drill 5 can be replaced during insertion by a needle 17 that hasa smooth tapered tip as shown in FIG. 8, and when the soft tissue hasbeen penetrated the needle 17 is exchanged for a needle drill 5 asdescribed in the invention. When the drill tip has reached the bonesurface, the drill is rotated manually or using a machine (not shown),and the drill is allowed to work its way through the hard cortical boneto the desired depth. As described in FIG. 6, the drill then occupies ahole which is larger than the outer diameter of the cannula, allowingthe cannula along with the drill to easily enter the drilled hole,whereupon the drill can be removed with the instrument's cannularemaining in the bone. In this simple and expeditious way, the cannulahas now been positioned like a fixed anchored guiding channel from theskin surface in through the corticalis to the lesion for furthersampling or treatment.

A considerable advantage with this method is that with the cannula in afixed position as a guiding channel, repeated biopsies can be performedin a simple way through the cannula. Various types of lesions requiredifferent types of biopsy needles in order to provide a satisfactorysample for analysis. Therefore it is of value, in instances of poorsample yield, to be able to change to a new type of biopsy needle andimmediately take a new sample.

Described here have been, primarily, the advantages of the punctureinstrument in relation to biopsy sampling, but in addition, it is alsosuitable for all types of radiological interventions ororthopedic-surgical procedures which require access to the bone throughthe corticalis. Administration of drugs and other substances can also becarried out in a simple way using the invention.

While specific embodiments of the invention have been described andillustrated, it will be clear that variations in the details of theembodiments specifically illustrated and described may be made withoutdeparting from the true spirit and scope of the invention as defined inthe appended claims.

What is claimed is:
 1. A device for puncturing hard tissue in humans oranimals, comprising:(a) a needle with a distal end and a proximal end;the needle having an outer diameter; (b) a drill tip disposed on thedistal end of the needle, the drill tip having a maximum diametersubstantially equal to the outer diameter of the needle, the drill tiphaving a drill point with a radial displacement in relation to an axialcenter of the needle, wherein the tip comprises a long cutter and ashort cutter in a same direction of rotation of the drill tip whenrotated, and the drill point formed at an intersection of the axes ofthe cutters; (c) wherein the long cutter extends to the outer diameterof the needle, and the short cutter extends to the outer diameter of theneedle; (d) a cannula, including a distal end and a proximal end,forming an axial void; (e) the needle being removably and rotatablyinserted within the void, having a length such that the distal end ofthe needle extends from the distal end of the cannula.
 2. The device forpuncturing tissue as claimed in claim 1, wherein the distal end of thecannula is externally tapered to an edge, and further comprising ahandle with an internal taper mounted on the proximal end of thecannula.
 3. The device for puncturing tissue as claimed in claim 1,further comprising:(a) a handle mounted on the proximal end of thecannula; (b) a second handle mounted on the proximal end of the needle;and (c) a connection on the handle to lock the cannula and needlerelative to one another.
 4. The device for puncturing tissue as claimedin claim 1, further comprising:(a) a handle with internal taper mountedon the proximal end of the cannula; and (b) a depth-stop mounted on theproximal end of the needle.
 5. The device for puncturing tissue asclaimed in claim 1, wherein the cannula is formed of a material having athickness less than the radial displacement of the tip.
 6. The devicefor puncturing tissue as claimed in claim 1, wherein the cannula and theneedle are coated with a friction-reducing material.
 7. The device forpuncturing tissue as claimed in claim 1, wherein the cannula and theneedle are coated with a hydrophilic coating.